I am having issues creating business procceses in Eclipse BPMN 2.0. The error Eclipse is showing is: "Message Event has no message definition". I really dont know where and how to fix it. WOuld be very thankful about your help.

You have added a MessageEventDefinition to a catch event, but the event definition does not reference a message type. You need to define a Message, and then select it in the MessageEventDefinition, like this: